This invention generally relates to motor vehicle safety restraint systems. More particularly, the invention relates to a safety restraints system having biomechanical gray zones, which defines the response of the restraint system depending on changes in velocity and occupant response.
Recent legislative changes have significantly increased the complexity of the required safety systems. These new requirements cover not only midsize adults but also small females and children. Advances in inflator technologies allow for the use of multilevel output air bag inflators. While these new inflators significantly improve occupant safety over a wide range of crash conditions, they also greatly increase the complexity of a systems design and performance.
In analyzing air bag system performance, it is useful to divide the system into three discrete regimes: 1. Information: acquiring information about crashes and occupants, 2. Analysis/Decision: analyzing that information to determine the nature of the crash and the circumstances of the front seat occupants, and deciding how to adjust the response of the air bag system accordingly, and 3. Response: adjusting the performance of the air bag (i.e. inflator) in response to the decisions regarding the acquired information.
Air bag systems acquire information through the use of sensors. All air bag systems have some kind of crash sensor indicating the occurrence of a crash and its severity. These systems process information from the sensors and use an algorithm to make decisions on the desired air bag deployment and performance based on predictions about the crash event. The systems may also have sensors, which provide information about such things as belt use, child seat use, occupant weight and size, seat adjustment position, and occupant location. The information from the sensors is used by the electronic control unit in making decisions as to whether and when the air bag is to be deployed. Air bag systems using these advanced technologies use the information to tailor the inflation levels of multi-stage air bags.
The information, analysis/decision, and response aspects of air bag systems each offer opportunities for improving occupant protection. With more and better information, improved decision-making algorithms, and greater adjustment capability to tailor the inflation, an air bag system can be designed to provide an improved response.
For example, with improved information about crash severity, the deploy/don""t deploy decision can be made earlier in a crash. By deploying earlier during a crash, before the occupant has moved very far forward, the air bag can better protect the occupant and is less likely to pose risks to the occupant. If an air bag system includes sensors, which provide information about occupant weight and/or size or location, it can be designed to suppress deployment in the presence of a young child or to deploy differently for small adults and large adults (e.g., a lower level of inflation for a smaller adult than that for a larger one). Critical to these advanced systems is the ability to deploy multilevel inflators at various levels depending on crash scenarios. The region where it is acceptable to deploy either low or high level outputs is the biomechanical gray zone.
Simulation studies using specific vehicle models and crash situations are used to define the biological gray zones. Impact velocity and restraint conditions are analyzed using occupant simulation models. In the example case, only in-position mid-seated 50th% (fiftieth percentile) occupant performance has been investigated; it is of course envisioned that the development of an actual restraint system with biological gray zones would include occupants of various sizes.
In view of the aforementioned challenges and design considerations, it is an object of the current invention to provide an air bag restraint system which will assess the difference in desired high and low level inflator output threshold speeds for belted and unbelted occupants.
It is further an object of the current invention to independently assess the high and low level inflator output threshold speeds for driver and passenger.
It is further an object of the current invention to identify the biomechanical gray zones for each type of occupant, inflator output and belt restraint.
It is further an object of the current invention to generate fire and no-fire diagrams.
It is further an object of the current invention to identify if the restraint system meets the occupant performance goals.